We report the synthesis, characterization, and gas adsorption analyses of a new charge-separated metal-organic framework (MOF), UNM-1 (C52H16BCuF16N4), possessing diamondoid structures, assembled from an anionic tetrahedral borate ligand and cationic Cu(i) metal ion. The resulting MOF structure displays four-fold interpenetration, resulting in high environmental stability, and at the same time possesses relatively large surface area (SABET = 621 m2 g-1) due to the absence of free ions. Gas adsorption measurements revealed temperature-dependent CO2 adsorption/desorption hysteresis and large CO2/N2 ideal selectivities up to ca. 99 at 313 K and 1 bar, suggesting potential applications of this type of charge-separated MOFs in flue gas treatment and CO2 sequestration.